1. Field of the Invention
This invention relates to linearly operated rotary actuators and, more particularly, to an integral rotary fluid coupling and a rotary actuator.
2. Prior Art
A rotary actuator provides rotational positioning for a tool or the like. The position of the output shaft of a rotary actuator is controlled by a reversible linearly movable element, which includes a fluid driven piston and single or double-helical splines or a piston-drive rack of a rack-and-pinion actuator. The rotating element, or output shaft, of a rotary actuator can advantageously rotatably position and support a hydraulic or pneumatic tool or powered implement. The fluid power and control sources for the tool are coupled to the tool from a power source remote from the tool. It is readily apparent that if fluid coupling lines are utilized, the lines may become twisted and wrap around the boom and the actuator when the tool or implement is rotated. Twisting and wrapping of the cables often limits the angular rotation of the tool.
Various types of slip joints which provide fluid coupling to rotatable equipment are known. For example, U.S. Pat. Nos. 3,908,695 and 3,966,249 disclose fluid slip couplings for tools or the like mounted at the end of a shaft. Such couplings are added externally or separate from the rotating or manipulating actuators, however, and increase the cost and particularly the length or size of the rotating actuators to the point where they are not cost effective.